Hello,

On 3/12/12 10:11 AM, Klaus Darilion wrote:

Hi!

Kamailio can count the number of calls per gateway and use the least loaded one.

not sure this is out of the box with carrier route module, but dispatcher module has call load balancing. Another option to track active calls per destination is using dialog module and profiles.

However, I would go with round robin and the failure route solution as pointed by Klaus, it is more flexible and lightweight.

Cheers,
Daniel

Another approach, which is more reliable uses failure-routing. This means, the load balancer chooses any of the gateways, but if the gateway response with a certain error code, the "failure_route" will choose the next gateway and re-sends the request. You can do the failure routing multiple times until you ran out of gatways.

regards
Klaus

Am 12.03.2012 10:00, schrieb Sasa Vilic:
Hello,

I have read here about load balancing between multiple gateways by using carrierroute module, but there is one particular question for which I found no answer.

Let's say I have two asterisk servers (X und Y), that are my gateways to PSTN. Let we do it simple. Let's say that each gateway supports only one outgoing call at the time and there is no incoming calls from PSTN. Now:

Bob calls one number and Kamailio uses X gateway.
Alice calls other number and Kamailio uses Y gateway.
Alice terminates the call.
Alice place a new call, but Bob's call is still in progress.
If we were used round robin algorithm, Kamailio would then use X gateway, but X gateway is currently occupied. What shell happen now?
And what if Alice didn't tear down call ordinary? What if it her SIP client simply crashed? (Then kamailio would think that there is now free gateway)

So the main question is: can kamailio know/detect, how much calls are going over one particular gateway and what can be done when limit for this gateway is reached?

Thank you in advance.

Kind Regards,
Sasa Vilic
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Daniel-Constantin Mierla
Kamailio Advanced Training, April 23-26, 2012, Berlin, Germany
http://www.asipto.com/index.php/kamailio-advanced-training/